Clearblue Pregnancy Tests
Clearblue offers a range of home pregnancy tests, all of which detect the clinically proven urinary pregnancy hormone – human Chorionic Gonadotrophin (hCG) to provide accurate and trusted results in early pregnancy testing.
How hCG is used to detect pregnancy
The hormone hCG is produced in the earliest stages of pregnancy. During early pregnancy it plays a role in survival of the corpus luteum1 and has a significant role in the implantation of the blastocyst and protection of the embryo against immune attack at the foetal/maternal boundary. The pregnancy hormone hCG is initially produced by the embryo and therefore acts as a marker for its presence.2
hCG levels rise rapidly and predictably in the earliest days of pregnancy3 and hCG can be detected in urine 9-10 days following estimated day of conception when using the most sensitive laboratory assays.4 The levels of hCG in early pregnancy have also been found to be highly similar between women.4 This makes hCG an ideal urinary marker for quickly and accurately assessing whether a woman is pregnant or not.
Clearblue Pregnancy Tests can be used up to 4 days before the period is due
Published literature shows that pregnancy hCG levels reach at least 50 milli-International Units per milliliter (mIU/ml) on the day a pregnant woman’s period is due.5-7 If a Clearblue Pregnancy Test is used from the day the period is due, it is more than 99% accurate in detecting pregnancy.8 Whilst Clearblue recommends that women test from the day the period is due, the high sensitivity of Clearblue Pregnancy Tests also means that pregnancy can be detected up to 4 days before the period is due for women who wish to test early. The graph below shows a typical rise in urinary level of hCG from the first detection of pregnancy.
Mean levels of hCG on days relative to the day the period was due (n=98 women)7
Not all pregnant women who test before the day their period is due will obtain a "Pregnant" result. This is because urinary hCG levels may not yet be above the threshold for the test.
Clearblue Pregnancy Tests are rigorously tested using early pregnancy urine samples from women whose luteinising hormone (LH) surge day is known and from which the day the period is due can be reliably estimated.7 Using these samples it is possible to assess the proportion of pregnant women expected to have sufficient hCG levels in their urine sample to generate a "Pregnant" result, on each day with respect to the day of expected period. If women choose to test early with the Clearblue Pregnancy Test, the likelihood of detecting pregnancy before the day the period is due is clearly displayed on the product packaging. Any woman who tests and gets a ‘Not Pregnant’ result, but still suspects pregnancy, should test again the day the period is due if testing was done early, or 3 days later if the period is overdue.
Clearblue pregnancy tests are over 99% accurate from the day the period is due
Pregnancy hCG levels can vary a little between women. However, if a Clearblue Pregnancy Test is used from the day the period is due, it is more than 99% accurate in detecting pregnancy.8 Circulating levels of hCG can increase with age in women, particularly around the menopause, and it has been proposed that this may lead to false positive results with pregnancy testing kits, particularly for perimenopausal women.9 Clearblue Pregnancy Tests have been tested using urine panels from peri and postmenopausal cohorts. None of the pregnancy tests were found to have a false positive rate over 0.5%.10 At Clearblue we believe that consumers need a result they can be confident in and act on, and therefore we provide pregnancy products that deliver over 99% accuracy from the day the period is due. Not all pregnancy tests are over 99% accurate from the day the period is due.
How hCG is used to estimate the time since conception
In order to demonstrate how hCG levels relate to the timing of conception it is important to conduct studies in which the day of conception has been accurately defined. Conception time can be estimated if the LH surge day is known in the cycle in which a woman became pregnant. LH surge is well validated as a marker of impeding ovulation,11-13 and ultrasound studies of follicular rupture have confirmed that the LH surge detected in urine occurs approximately 24-36 hours before ovulation.14 As the egg survives for only around 0.7 of a day,15 and the fertile period ends on the day of ovulation,16 conception occurs shortly after ovulation. Therefore detection of the LH surge can be used to estimate the day of conception. Collection of urine samples from complete menstrual cycles in which the volunteer became pregnant and the LH surge is known can demonstrate the utility of hCG in providing an estimate of time since conception.
Following implantation, hCG levels rise exponentially and predictably in blood and urine so hCG has been used to estimate gestational age.17,18 Rigorous trials have shown that there is a consistent pattern to urinary hCG levels in the first few weeks following conception19 such that thresholds for the urinary hCG hormone can be assigned in order to determine time since conception in categories: 1-2, 2-3 and 3+ weeks since conception. These thresholds are employed by the Clearblue Digital Pregnancy Test with Weeks Indicator, so that the test provides not only a "Pregnant"/"Not Pregnant" result, but also an estimate of the time since conception. Furthermore, pregnancy duration estimates using the Clearblue Weeks Indicator result are 98% in agreement with standard of care ultrasound results when ultrasound precision is taken into account.20
Digital displays provide more accurate readings
It has been shown that one in four women can misread traditional line pregnancy test results.21 The Clearblue Digital Pregnancy Test with Weeks Indicator contains an optical reader which provides clear digital results and eliminates the human error that can occur when reading traditional line pregnancy tests.21
The one-piece Clearblue Digital Pregnancy Test with Weeks Indicator provides women with several important benefits:
It confirms whether a woman is pregnant with over 99% accuracy from the day the period is due22
It is unique - the ONLY pregnancy test that can estimate time since conception
It is sensitive enough to be used up to 4 days before the period is due23
It agrees 98% with estimation of gestational aging by routine ultrasound* 20
It is reliable – based on established technology
It is easy and convenient to use
It is trustworthy - Clearblue, the world's number one selling brand in home pregnancy and fertility testing
It provides a simple result in symbols: "+" for pregnant or "- for not pregnant
Clearblue PLUS Pregnancy Test – as accurate as a doctor's urine test24
The innovative Clearblue PLUS Pregnancy Test offers six important benefits:
It has an ergonomically designed handle, designed to make the Clearblue PLUS Pregnancy Test the easiest home pregnancy test to use
Its Colour Change Tip helps women to perform the test more easily
Its integrated Flood Guard helps women to use the test correctly
It is over 99% accurate at detecting pregnancy from the day the period is due25
It provides an easy-to-read + or − result in just 3 minutes.
It is sensitive enough to be used up to 4 days before the period is due26